Method of producing luminous dials for clocks and watches



Nov. 23 1926. 1,607,822

' c. H. GRANGER METHOD OF PRODUCING LUMINOUS DIALS FOR'CLOCKS ANDWATCHES Filed'April 13, 1926 Patented Nov. 23, 1926.

'U'Nl'T E STAT ES JATENT arr-cs.

CHAR-LES H. GRANGER, OF WATERBUB' Y, CGNNECTIGUT, ASSIGNOR T0\VATER-BURY CLOCK 00., OF WATER-BURY, CONNECTICUT, A CORPORATION.

METHOD OF PRODUCING LTJMINOUS DIALEi FOR CLOCKS AND WATCHES.

Application filed April 13, 1926. Serial No. 101,856.

This invention relates to improvement in method of producing luminousdials for clocks and watches. Heretofore, luminous dials, so-called, forclocks and watches have generally been laboriously produced by themanual application with a fine brush of a paint containing a modicum ofradioactive material to dial-numerals previously printed upon the dialsin the usual manner with ink or some substitute therefor. his method ofapplying a modicum of radioactive material to dial-numerals isexcessively delicate and laborious, and such is the apprehensionregarding the character of the material in its effect upon the health ofthe workers that great difficulty has been found in securing girls, bywhom such work is done, to carry it on. The method above described isalso objectionable on account of the expense, the impossibility ofsecuring a film of uniform thickness upon the numerals, as well asproducing numerals of sharp definition or clear-cut edges. The object ofmy invention is to not only overcome the objections above recited, butalso to produce luminous clock and watch dials of superior appearanceand effectiveness, due to the application of the material in relief withuniformity of thickness and sharpness of outline.

With these ends in view, my invention consists in a method of producingluminous dials for clocks and watches consisting in cuttingdial-numerals in intaglio in a suitable die, then filling the intaglionumerals so out with a composition radioactive luminous materialcombined with an adhesive carrierand then transferring the said materialunder pressure to the flat surface of a clock or watch dial.

In the accompanying drawings:

Fig. 1 is a view in elevation of a watchdial produced by following myimproved method;

Fig. 2 is an enlarged broken sectional view thereof on the line 2-2 ofFig. 1;

Fig. 3 is a plan view of the die employed and V 1 Fig. 4 is an enlargedbroken view thereof on the line 4-4 of Fig. 3.

In carrying out my invention, a metal die 5 of suitable size iscarefully engraved in intaglio with dial-numerals 6 of suitable designand size for the particular character of clock or watch dial to beproduced. The intaglio dial-numerals of such a diev are then filled withwhat, for want of a better word, I may calla luminous ink, composed ofradioactive material in the form of fine crystals, such material beingcombined with an adhesive carrier, which may be similar to printers inkbase. The die is now wiped as in printing, and the remaining luminousink in the dial-numerals transferred, under pressure, in a suitableprinting press, to the flat face of the clock or watch dial 7 to beproduced, which, consequently, has imposed upon it, in clear-cut relief,corresponding to the depth of the intaglio dialnumerals cut in the die,a series of sharplydefined luminous dial-numerals 8 of uniformthickness, and much sharper in outline than any dial-numerals painted byhand with a brush can be. Moreover, the luminous material when appliedin this manner in clearcut relief, is more condensed and effective thanwhen manually applied by means of a delicate brush, for the reason thatwhereas the material, when applied with a brush, presents only a flatsurface for supplying illumination, its edges being negligible, imposednumerals applied under my improved method present bold edges as well topsurfaces for supplying illumination.

By this method, the objection raised by the girls, who heretofore havedone such work, to the supposed danger to health from handlingradioactive material, to which considerable' avoided.

I am aware that it has been proposed to print clock-dials by theso-called offset process of printing, which consists in first printingupon an intermediate sheet of flexible material and then transferringthe ink applied thereto to the ultimate surface to be printed. However,the so-called offset process of printing is not available for theimposition upon a dial of luminous dial-numerals in marked relief withclearly defined. edges, such as it is the object of my invention toproduce.

I claim:

A method of producing luminous dials mystery attaches, is entirely ,forclocks and watches consisting in cutting dial-numerals in intaglio in asuitable die, then filling the intaglio numerals so cut with acomposition of radioactive luminous I material combined with an adhesivecarrier,

and then transferring the said material under pressure dlrectly to theflat surface of a CHARLES H. GRANGER.

